Tidal and subtidal interaction between riverine and ocean forcings in a subtropical estuary

Near year-long time series of water level elevation from 7 stations along the Suwannee River, Florida, were used to characterize, observationally and analytically, the tidal and subtidal signal propagation along the estuary. Tidal amplitudes and phases were obtained from least squares fits and used to fit an analytical model. Subtidal modes and their phases were obtained through Hilbert Empirical Orthogonal functions and also compared to an analytical solution. The attenuation of the tidal signal as it propagated upstream was replicated analytically. The subtidal signal was also described analytically with two waves traveling in opposite directions (landward and seaward). The analytical solution represented very well the competition between the two waves and also their zone of dominance. The amplitude of the competing subtidal waves increased from the landward. Depending on the phase of these waves, the resulting subtidal wave amplitude could dampen and then increase landward, or amplify and then decrease.